Reheating furnace



Much 8, y1932. A. SIPRENGER v 1,848,231

REHEATING FURNACE Filed Feb. 20, l1929 2 Sheets-Sheet. 1

March 8, 1932. A. sPRr-:NGER

REHEATING FURNACE Filed Feb. 20. 1929 2 Sheets-Shea?I 2 Patented Mar.; 8, Y1932 rsiazn .ARTHUR- srnnNGEie, erfv,isnlenrN-camareramienne, @K ernaarANY'Y,"y assreNoiaf'rfoA .Fnrnnnrcir SIEMENS AxrrnN GESELLSCHAFT; cF BERLIN; GERMANY' REHEATING rUaNacEx u 'Application mea February 2o, 1929;' serial No. 314,414, and meermalny neeemberii, 192s.

Y y -Modernrolling mill lpractice imposes ever increasing demands i onfrlthe average Voutput *capacity of relieating furnaces Vfor .ingots, a requirement which, however;`

with theY fur-y nace constructions now in use can only'be .used by increasing they 'number-f of .furnaces. -Thls expedient can 1n ymost ,cases-not' be adopted,Y ovvingk te lackef space. For the Y same reasonthe Aotherwise obvious expedient of increasing the length `f the reheating fur-` naces finds'ia limit which cannotbe exceeded. According to this invention a solution'of the problem yof increasing the output of reheatingfurnaces'is found Without increasing` the 4space required.

The gradual, uniformly increasing heating of the ingots is e'eetedbya flame sweeping through the furnace from thedischarging end to the charging end in a uniform direction, ,the ingots travelling 4,throughY vthe furnace in opposition to the direction ofthe vflame. For producing this "singlefdirection flame burners ofanyform whichl are fed directly With coke-oven gas, producer gas or the-like may be used. 'W ithj such an arrangement a Vdeliniterather' loav limit for the length y .of the oven may not befexceeded, as the flame streaming inte the furnace yfrom-the burners first comes in contactat the discharge end Withthe most highlypreheated ringots and must inet 'heat these toe fiercely, as thereisKV otherwise the danger of too great a lossrof material' through burning. i, f y

' A far more economical manner of Working such reheating furnaces canv be effected Yby usingl a regenerative method oflheating, in which a portion ofthe reversible regenerative llame is branched olf, which svvveepsthrough' the' furnace right to the chargingY end Without lchanging its direction.` For obtaining its full effect this flame Aof course requires a certainflength offurnace. Thisflen'gth may, however, not kbe exceededfand it has,y

Ytherefore already been proposed to provide, vstarting from the discharging end `of the furnace;u several burners l one behind the other in Ythe-furnacearch or inthe; side walls-hf the furnace, through which. portions Yobtained 'inlV the furnace output, but this inof the entire furnace `flame or additional;v

QamesfV are ,introduced intothe furnace. In' 0 creasein the length of ,the furnaceextends substantially to the-hottest par-V"J of Vthe, vfurnace, formerly called the Welding hearth, so

thatfthere is they danger of 'anf increased amount of waste; Furthermorezit yis not possible in thisway to obtain in the hottest vpart of thefurnacefthevvelding hearth) a uniform` increase in temperature, fas With a,

single flame, since at each ofgthe burners arranged one behindthey other the flameV there entering formsaa certain maximum, sorthat theceurse ofthe temperature curve ofptheir` Y oventowards rvthe discharging end would not `b eregularelcut undulating.l j vlt, has also been" proposed to divide` the re- *j heating furnace, say bywapartitlon or Ain some and thebuddle or preheatling' hearth and to' provideeach of these hearths l'With separate .regenerative .firing. This furnace construction,r however, :also hasV considerable 4disadvantages In therst place 'the accessibility f 7'5 f of thefurnace is considerably interferedvvith hy the necessary 'lateral arrangement ofthe regenerative firing for the buddle,"while on rate Aregenerative ringpass to thewelding hearthuat a too high temperature,' rs0 that there must be considerable Wastage in this part ofthe furnace or, if this disadvantage is to be avoided, there Will be a break, at the place kvv'herethe buddle merges into the Welding hearth, inthe uniform increase in temperaturefwhich must also be regarded as undesirable.` v

The desired increase in the output of `reF l,

heating furnaces is realized according to the present invention, while the disadvantages attaching to the hitherto known constructions of such furnaces are avoided both as regards the lateral accessibility of the furnace in the neighbourhood ofthe discharging end and as regards the uniform heating, more particularly in the hotter part of the furnace by the uniform flame which enters the hotter part of the furnace at the discharging end and sweeps through the entire furnace being supplemented in the colder part of the furnace, thatis towards the charging end,..by additional heating means suitably consisting in a plurality of burners lyingone behind the other in the longitudinal direction of the furnace, which enables flames which gradually increase in heating energy to be introduced into this part ofthe furnace. In a preferred way of carrying out the invention the additional heating is caused to act transversely of the axis of the furnace, in which case it can be regenerative, by the combustion airbeing preheated, while the gas is-supplied in regulable quantities tothe separate burners increasing towards the discharging end in the manner described above. The waste gases from this additional y heating may then be passed to regenerators which may also receive the waste gasesof the single-direction flame sweeping through the entire' furnace. If-the latter, yas explained above, be branched off from a regenerative furnace or flame the waste gases of theadditional heating may be introduced yas a whole or' inl part into the regenerators ofthis regenerative heating system, so that the combustion air required for the additional-heating may be taken from these latter regenerators as well. In 'this case separate regenerators for the additional heating may of course be provided from the regenerators of the regenerative heating system producing the single-direction flame of the furnace.

' Two constructional examples of the invention are shown in the accompanying drawings, in which Fig. 1 shows a furnace according to the invention in vertical longitudinal vsection with regenerative heating for the single-direction flame,

Fig. 2 being a horizontal longitudinal sec- -tion of Fig. l.

Fig. l3 shows a second constructional form of furnace according to the invention with ordinary burners for producing the singledirection flame, in vertical longitudinal section,

Fig. 4 being a horizontal longitudinal section of Fig. 3. y

Fig. 5 is a horizontal section on the line 5-5`of Fig. 1 showing the gas nozzles for supplying combustible gas to the furnace shown in Figs. l and 2.

,f AIn the constructional form of furnacefaccording to the invention shown in Figs. l and 2 the air enters through a butterfly valve a', flows alternately through the regenerative chambers Z2 and c and passes for instance from b through the flue d into the horizontal passage e lying above the end of the furnace. That portion of the air which is to be mixed with the combustible gas to produce the flame to heat the material is drawn by suction from e through the suction of the combustible gas flowing out of f through the nozzles h and is passed into the furnace space Vproper g, forming a flame. The combustible gas is fed under pressure to the separate nozzles h. At the other yend the passage e com municates through the flue Z with the regenerative chamber c so that a portion of the hot combustion air may here flow out of e through Zinto the regeneratorc. For heating the regenerators the flues d and l are provided with gas supplying means provided with a gasbutterfly valve 0 and a gas supply pipe n so that each of the regenerators 'may be heated alternately by a separately formed flame. n

According to the invention near the charging end of the furnace a plurality'of burners p are provided, which as shown in Fig. 2 lie in pairs opposite one another. The burners 72 communicate through vertical passages g with the regenerators b and c and are supplied through separate gas pipes r with the requisite combustible gas in a regulable manner. The gas and air supply to the burners p must also be reversible and for this purpose they are supplied with air which enters through a butterfly valve a and flows alternately through the regenerators 1) and c', each of 'which is supplied with combustible gas through an'independentset of pipes r, the arrangement being such that the Waste gases pass from the furnace into the regenerator b or c situated opposite that one which for the time being .receivescombustible gas fromfits pipes r and air through the valve a. Any residual waste gases are carried by the air entering from the outsidej ust behind the charging door through thezopenings and the passages le to the chimney.

` As the burners p vreceive their combustion air from the regenerators b and c heated by the well-known refining flame and as, on

`the other hand, the gas can be supplied in an arate regeneratois A kbutterfly valve a must then be provided for the regenerative heating means of the single-direction Haine.

The constructional form ofthe invention shown in Figs and 4 differs from that just t described solely in a differentway of progots travelling through the furnace.4 In the colderY parts ofY the furnace towards -the charging end, burners p supp-lied with gas through pipes r and heated air through passages g are. also provided. The waste gases of the single-direction flame pass alternately y y through the passages Q with the waste gases of the additional' heating burners p into the regeneratorsfbg, Vc2, which in this construction extend Vover the greater part of the length of the furnace and yto'which air is alternately supplied through the butterfly valve a.. The'fconstruction and operation of the `burners p is the same as Vthat of the corresponding burners p in Figs. 1 and 2.

rIhe regenerators c, b1, cl and b2, c2 are tted internally with checkerwork 6.

The flue 7c at the end of the furnace serves principally for removing the cold air which enters the iurnace through the charging door I l and the residual waste gases.

In the additional heating system of the furnace here shown the successive flames enter the furnace, 'according to how they are regulated, from one side or the other, sothat in consequence rthe ingots as they move through the furnace at right angles to this flame are 'heated in their longitudimilV direction Valternately from one end and from the other." rIhis is, however, only an apparent disadvantage which V is compensated to a certain degree by the single-direction flame of the furnace, which. coacts with the additional heating system. In the hotter part of the furnace the ingots preheated by the additional heating system yare heated through in a completely Vuniform manner by the singlerdirection iiame which in this part acts with Y its full energy, so that this initial inequality in heating is of practically no importance. What I claim is: l. A reheating. furnace for ingots, comprising thecombination with a heating chamber having a charging opening at one endv` and a discharging opening at the other end andmeans for introducing acoinbustible mixture intosaid heating chamber in proximity to said discharging opening, for causing a `single-directionllame to sweep through the 'heating-chamber towards thecharging opening, of means. for admitting-a combustible mixture into said heating chamberin the porcharging opening, as andfor the purposes set forth.rvr t t 2. Afreheating-furnace for ingots', comprisving the combinationwith a heating chamber having-a charging yopening at one means Efor introducing 'a ycombustible ymixture into said heating chamber in vpror'iiiiiity to said discharging opening, for causing a single-direction flame to sweep through the heat-` ing chamber towards the charging opening, ofmeans arranged in the side of the heating chamber forfadniitting a combustible mixture into said heating` chamber in the portion thereof in` theneighbourhood of the said,

charging opening so as to cause a heating ame' to pass across the heating chamber at right angles to the longitudinal laxis thereof, as and for the purposes set forth.V

,3. A reheating'furnace for ingot-s,-co`mpris ing the combination with a heating chamber having a charging opening at one endand a discharging opening at the other end, a burner arranged'at the end of the heating chamber in proximity to said discharging opening for introducingl a combustible mixortion of the heatingA chamber Vas and for the purposes set forth;

4. A relieating furnace for ingots as set combustion from the heating chamber, means connected to said regenerative heating means l andto the burners arranged near the chargtion thereof inthe 'neighbourhoodof the said` end and a dischargingopening at theother end and ecv forth in claim 3, having a pair of regeneraf tive air heating means adapted to be heatedV by the passage therethrough of products ofv 'iie chamber and said regenerative heating means,

air supply means foradmitting air to eac-h of said regenerative air heating means, con'- trolling means interposed in said air supply means for shutting oif the air supply to each of saidregenerative air heating means alternatively and means for supplying combustible gas to the burners, as and for the purposes set forth.

5.k A reheating furnace for ingots asset forth in claim 3, having a set of regenerators adapted to be heated by the passage therethrough of products of combustion from the heating chamber, means 4connected to the f burners arranged k.near the charging opening for establishing open communication between said burners, the heating chamber and said regenerators for 'admitting combustion ases tothe regenerators from the heating c amf ber, and admitting air to said burners from the regenerators, means connected to said regenerators and to the burner situated n proximity to the discharging end of the heating chamber for admitting air to said burner from the regenerators, and means for supplying combustible gas to the burners, as and for the purposes set forth.

In testimony whereof I have signed myy name to this specification.

ARTHUR SPRENGER. 

